Need high CFM fan, one speed
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
Need high CFM fan, one speed
Can someone recommend a pc fan with 250 CFM that runs at ONE speed? I already bought one but it keeps revving up and down. The fan will be used for a homemade air filter system.
Does a 3-wire fan mean it only runs at one speed?
Your info is appreciated!!!! Thanks!
Does a 3-wire fan mean it only runs at one speed?
Your info is appreciated!!!! Thanks!
Re: Need high CFM fan, one speed
Welcome to SPCR.
2-pin fans: Vdc, Ground
3-pin fans: Vdc, Ground, sensor (for rpm)
4-pin fans: Vdc, Ground, sensor, PWM signal
Even a 2-pin fan can ramp up and down if the source that it's plugged in to is ramping the Vdc pin voltage up and down.
2-pin fans: Vdc, Ground
3-pin fans: Vdc, Ground, sensor (for rpm)
4-pin fans: Vdc, Ground, sensor, PWM signal
Even a 2-pin fan can ramp up and down if the source that it's plugged in to is ramping the Vdc pin voltage up and down.
Re: Need high CFM fan, one speed
Thanks for the reply. So....if I am understanding this, I would be safe with a two pin fan that would run at it's highest rpm constantly? I'm using a converter 110v to 12v. I am using another pc fan 125cfm on the same converter and it runs without it revving up and down. Thanks!
Re: Need high CFM fan, one speed
Yes. Make sure the 110V to 12V converter is providing 12Vdc and not 12Vac.
If you want to manually control the fan speed, you can always get a Fan Mate. I've used them in the past when motherboard fan controls were non-existent/poorly done.
Another method is to find a fan that runs at a speed you like when driven by 5Vdc. Then, just cut the end off of an old USB phone charger. High efficiency, cheap.
Re: Need high CFM fan, one speed
Another thing you can do is find a fan that'll run at a speed/cfm you like when driven by 5Vdc. Then, grab an old USB phone charger (pre USB-PD spec = 5V output) to run it.
Re: Need high CFM fan, one speed
Thanks gents! Great info. I just want the fan to run full speed all the time. I'll shut it on and off with a remote. So again....will a two wire 250cfm fan run at it's highest speed off the 12v converter, without revving up and down?? Will a three wire fan do the same only wiring the black and red wires? I just don't want to spend the money again, because the 250cfm fan I bought had 4 wires, and no matter how I tried wiring it, it still revs up and down.
Thank you!!
Thank you!!
Re: Need high CFM fan, one speed
yes to both.
Re: Need high CFM fan, one speed
OK thanks but....if that's the case then why does my 4-wire 250cfm fan rev up and down with only the red and black wires hooked up? I just don't know exactly what type and name of fan that I should order to get around this problem.
Re: Need high CFM fan, one speed
Yeah, I don't know what's up with your fan, but you might check the supply to see if it's a stable 12Vdc source.
As far as a specific fan goes...250cfm? really? Anything less than a 200mm fan will be spinning like crazy / really loud for that.
Using Noctua fans as an example:
NF-A20-FLX is 200mm, has a max speed of 800rpm, and provides ~245cfm. noticeable noise.
NF-A14FLX is 140mm, has a max speed of 1200rpm and provides 192cfm. probably noisy.
NF-A12x25 FLX is 120mm, has a max speed of 2000rpm and provides 170cfm. probably very loud.
As far as a specific fan goes...250cfm? really? Anything less than a 200mm fan will be spinning like crazy / really loud for that.
Using Noctua fans as an example:
NF-A20-FLX is 200mm, has a max speed of 800rpm, and provides ~245cfm. noticeable noise.
NF-A14FLX is 140mm, has a max speed of 1200rpm and provides 192cfm. probably noisy.
NF-A12x25 FLX is 120mm, has a max speed of 2000rpm and provides 170cfm. probably very loud.
Re: Need high CFM fan, one speed
I really appreciate you taking the time to explain this to me! Very good info! Good idea about checking the 12Vdc source. I will be ordering one of those Noctua fans. Thanks again!!!!!!!
Re: Need high CFM fan, one speed
If it's a dense filter you might be looking more at a fan capable of building pressure rather than moving free air.
Because there are shifts in the restriction/flow of air?
To keep the fan running at a constant speed you either need a static setup with constant voltage and constant pressure gradient or have some regulator controlling the fan speed to keep it (near) constant.
Re: Need high CFM fan, one speed
Thanks for the reply. I fixed the revving up and down problem. I ordered a 110v to 12vdc converter that puts out 5amps and the fan is blowing like a hurricane now. Just needed more amps. Old converter only had 1 amp.